To find \( f(-4) \) given the function \( f(x) = x^2 - 3x \), we can substitute \(-4\) into the function:
\[ f(-4) = (-4)^2 - 3(-4) \]
Calculating each term:
- \( (-4)^2 = 16 \)
- \( -3(-4) = 12 \)
Now, combining these results:
\[ f(-4) = 16 + 12 = 28 \]
So, the answer is:
28